Coating & Laminating Sustainability in lamination without
compromising equipment efficiency Sustainability and the move to replace non-recyclable multi-material packaging with recyclable alternatives are progressing at full speed in a plastics industry that is undergoing one of the biggest global transformations ever as this report from Bobst explores.
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rowing consumers’ awareness towards packaging sustainability and brand owners’ pledges towards recyclability have spurred advances in water-based and solventless lamination technologies, as well as the introduction of new substrates and adhesives that require higher flexibility in the converter production halls and the capability of the equipment to handle them. Bobst’s actions in this respect are in full swing in its competence centres – in the past years Bobst has developed with different partners along the value chain various process solutions for a new generation of high barrier mono-material polyolefin laminated structures.
“Machinability is an important aspect of new consumables that need to be thoroughly tested to ensure they can become viable commercial products on the one hand, delivering superior results in terms of optical quality and performance of the output so that they meet the brand owners’ and consumers’ expectations. They should also meet the requirements of converters in terms of efficient production at speed so as not to affect the profitability of their operations,” explains Davide Rossello, head of competence centre and process manager Gravure at Bobst Italia, Bobst’s center of excellence for gravure, lamination and coating technologies.
One recent project, now close to industrialisation, is a collaboration between Ticinoplast and Plastchim-T, (respectively leading producers of blown PE and BOPE), Sun Chemical for new formulation adhesive and lacquer and Bobst for the laminating equipment for the production of a high quality, high barrier, printable BOPE mono-material structure.
The tests were carried out on Bobst coating and laminating lines – the multi-technology Vision D 850 and the solventless Nova SX 550 – as well as the Master RS 6003 gravure press. The equipment role was also to identify the critical points of the processing flow and consumable metering and to prepare technical solutions to overcome them, with ad hoc electronic developments and interventions on the handling of the film, but also with particularly
advanced components for the application of the water-based lacquer and the solventless adhesive. Meeting the critical requirements of water-based product processing: coating and drying To strengthen the PE’s oxygen barrier a water- based coating was applied by the Vision D 850 laminator. The new formulation lacquer has a low degree of solid content so it must be metered in a consistent and precise way to avoid the formation of bubbles, foam, or other defects. Different coating methods were tested taking into account converters’ preferred systems. Excellent oxygen barrier results were achieved using the new generation Bobst designed pressurised doctor blade coating system, as well as with the more conventional gravure coating system with smoothing bar. In the pressurised doctor blade chamber, the lacquer is kept under pressure by a system of pumps and comes out with absolute homogeneity and fluidity that enable superior optical quality up to 300 m/min high speed processing.
By integrating the latest design concepts, the Bobst pressurized chamber doctor blade also offers a wider coating weight range and minimises the shear stress that affects performance. Highly flexible, it can be used on both integral and trolley type versions of coating units, and it is very fast to set up and changeover.
Drying was another critical aspect of this project. It must be effective and very precisely controlled
on two counts: on the one hand, water-based consumables – be they coatings, adhesives, or inks - require significant heat to dry. On the other hand, however, it is necessary to avoid the overheating that would be damaging for the BOPE substrate, even if biorientation has conferred additional stiffness to the thermosensitive PE film. The Vision D 850 laminator tunnel features a double technology airflow and it is divided into the 3 sections. This enables adjustment of the temperature of each section as required. The combination of this type of tunnel with the pressurized doctor blade allowed us to reach the notable speed of 300 m/min Bobst has developed a unique system that controls and adjusts in real time the web strain level along the whole web path of the machine, to avoid excessive elongation that damages barrier properties on critical substrates.
Lamination trials with Sun Chemical’s new formulation solventless barrier adhesive were carried out on the Nova SX 550, a compact solventless machine. Application of the adhesive also done at a high speed, delivering a flawless quality finish, furthermore owing to the exclusive configuration of the Bobst solventless coating system, with unique anti-misting geometry together with the laminator’s extremely precise web-handling capabilities. Sustainability, along with connectivity, digitalisation, and automation, is one of the four cornerstones of the Bobst vision focused on changing the future of the packaging world. Industry collaborations with an ecosystem of partners are key elements to the implementation of this vision.
Several projects and research and development trials, each with its ecosystem partners are taking place in Bobst Competence centers and laboratory facilities. Some projects have already reached industrialization. Many more are showing promising results across different technologies and processes, taking advantages of the synergies within the Bobst Group and the partners, and will be presented in 2022.
Xwww.bobst.com
14
November 2021
www.convertermag.com
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